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At least 811 records · Page 45Linked to original sources
PubMed1994

Localization of atrophy-prone areas in the aging mouse brain: comparison between the brain atrophy model SAM-P/10 and the normal control SAM-R/1.

Mouse inbred strain "SAM-P/10" (Senescence Accelerated Mouse) is a model of age-related brain atrophy. In this strain there is an earlier and more severe age-related deterioration in the conditional avoidance learning than the normal control inbred SAM-R/1 strain. The present study analysed age-related changes in brain area size using a computerized morphometric method. The region most vulnerable to age-related atrophy in SAM-P/10 was the frontal region of the cerebral cortex, including the prefrontal cortex. Other neocortical regions underwent diffuse atrophy. Posterior piriform cortex, entorhinal cortex, anterior olfactory nucleus, amygdala, caudate-putamen, nucleus accumbens and cerebellar cortex were atrophy-prone regions. The septum also underwent atrophy but other basal forebrain structures were intact. The hippocampus, diencephalon and brainstem structures showed no atrophic change. White matter structures did not change in size with aging except for the forceps minor of the corpus callosum, which showed age-related atrophy. On the contrary, SAM-R/1 showed a significant age-related atrophy only in a restricted part of the cerebral cortex, mainly in the parietal region. Other cortical regions, subcortical structures, diencephalon, brainstem structures, cerebellum and white matter were atrophy-resistant in SAM-R/1. The prefrontal cortex, entorhinal cortex, piriform cortex and striatum are closely interconnected and also connect with the amygdala which plays a key role in conditioning in the rodent. Age-related atrophy in all these structures in SAM-P/10 presumably accounts for the age-related deficits in conditional avoidance learning in this strain of mouse. Comparison between SAM-P/10 and SAM-R/1 or other well-known rodents indicates that SAM-P/10 is a unique rodent that spontaneously and rapidly develops progressive generalized cerebral atrophy, which is considered to be a pathological process rather than an accelerated aging process.

Aging↗
PubMed1999

Argyrophilic dark neurons distribute with a different pattern in the brain after over hours treadmill running and swimming in the rat.

Argyrophil III staining is a useful method for the detection of dark neurons (DNs) that would reflect an early cytopathic feature. We examined the appearance of DNs following the stressful exercises (0.5-3 h swimming in a pool of 25-45 cm depth; 1-2 h running on a treadmill at the speed of 600-1200 cm/min) in the rat. After the swimming, DNs were detected in the hippocampus (CA1-2 pyramidal cell layer, oriens layer), somatosensory cortex, entorhinal cortex, hypothalamus, habenular nucleus, amygdaloid nucleus, striatum, accumbens and sometimes in lateral septal nucleus. After the running, DNs appeared in the visual cortex, deepest layer of area 17 and 18a, motor cortex, red nucleus, somatosensory cortex, entorhinal cortex, and hippocampus (dentate gyrus). Thus, the DNs appeared mainly in the limbic structure after the swimming, and in the limbic structure, motor-related regions and visual cortex after the running. Further, the number of the DNs and the extent of area where they distributed were dependent on the strength and the duration of the exercises. In hematoxylin-eosin (H-E) staining, we often detected pycnotic cells (dark stained soma) in CA1 hippocampus where argyrophil positive cells were most abundant. The picnotic cells were not so common in other areas. Data suggest that DNs are induced by stressful exercises. They might reflect an early cell injury following stress and overexcitation.

Animals↗
PubMedDate not supplied

Spreading of epileptic afterdischarges between entorhinal cortex and hippocampus in acute experiments and the kindling model of epilepsy in the rat--comparing different methods of analysis.

Spreading of epileptiform activity in the central nervous system is one of the fundamental problems in epileptology. The patterns of spreading of after-discharges in the hippocampus and entorphinal cortex were studied in acute experiments and using the kindling model of epileptogenesis. Three methods were used to determine the time relations between EEG signals from different brain areas; visual inspections, average amount of mutual information (AAMI) and phase spectrum method. The analysis methods used are adequate for quantification of the degree of coupling between different EEG signals during an afterdischarge, but should be used jointly since different signal features are taken into consideration by different methods. During an afterdischarge only at the beginning the focal area is clearly leading the other brain areas; thereafter the pattern becomes more complex.

Animals↗